It’s 1940, France has fallen, and only a narrow strip of sea lies between Great Britain and invasion. The country is in peril. What’s needed (obviously) is a morale-boosting, heart-warming war film, preferably one that will appeal to the American market.

As bombs start to fall on London, work begins on ‘Just an Ordinary Wednesday’, an almost-true tale of bravery and rescue at Dunkirk. And since call-up has stripped the film industry of the brightest and best, it’s the callow, the jaded and the utterly unsuitable who are making up the numbers.

There’s Catrin Cole, junior copy-writer turned romantic dialogue specialist; Ambrose Hilliard, third most popular British film star of 1924, currently available for all leading roles; Edith Beadmore, ex-seamstress at Madame Tussaud’s and ex-Londoner, having been bombed twice in two months; and Arthur Frith, whose peacetime job as a catering manager hasn’t prepared him for his sudden, unexpected elevation to Special Military Advisor.

And in a serious world, in a nation under siege, in a city visited nightly by destruction, they must work together to produce a slice of the purest entertainment . . .